The grid (View > Grid and Helplines > Display Grid) is showing tiny dots that become barely perceivable when zooming in. It was suggested on the mailing list https://listarchives.libreoffice.org/global/design/msg08925.html to change the dots to symbol such as a plus that increases it's size on zoom. This idea is supported by the design team.
Reported in bug 120720
*** This bug has been marked as a duplicate of bug 120720 ***
*** Bug 120720 has been marked as a duplicate of this bug. ***
(In reply to Xisco Faulí from comment #2)
> *** Bug 120720 has been marked as a duplicate of this bug. ***
It was actually the original and attachment 145842 [details], attachment 145843 [details], and attachment 145875 [details] are quite useful.
"Writer, Calc, Impress, Draw" all use this grid design.